Concept Guide

ipv6 mld explicit-tracking
Reducing Leave Latency
Leave Latency is the amount of time after the last host leaves the MLD group that the router stops forwarding trac for that group.
Latency is introduced because the router attempts several times to determine if there are any remaining members before stopping trac
for the group. The Querier sends a Multicast-Address-Specic Query upon receiving a Done message to ascertain whether there are any
remain receivers for a group. The Last Listener Query Interval is the Maximum Response Delay for a Multicast-Address-Specic Query, and
also the amount of time between Multicast-Address-Specic Query retransmissions. Lowering the Last Listener Query Interval reduces the
time to detect that there are no remaining receivers for a group, and so can reduce the amount of unnecessarily forwarded trac.
To adjust the last-member query interval, use the following command:
INTERFACE Mode
ipv6 mld last-member-query-interval
Displaying MLD groups table
Display MLD groups. Group information can be ltered.
To display MLD groups, use the following command:
EXEC Privilege
show ipv6 mld groups
Dell#show ipv6 mld groups
Total Number of Groups: 1
MLD Connected Group Membership
Group Address Interface Mode Uptime Expires Last Reporter
Ff08::12 Vlan 10 MLDv2 00:00:12 00:02:05 1::2
Displaying MLD Interfaces
Display MLD interfaces.
To display MLD interfaces, use the following command:
INTERFACE
show ipv6 mld interface vlan 20
Dell#show ipv6 mld interface vlan 20
Vlan 20 is up, line protocol is up
Inbound MLD access group is not set
Internet address is fe80::92b1:1cff:fef4:9b63/64
MLD is enabled on interface
MLD query interval is 60 seconds
MLD querier timeout is 125 seconds
MLD max query response time is 10 seconds
MLD last member query response interval is 1000 ms
MLD immediate-leave is enabled for all groups
MLD activity: 0 joins
MLD querying router is 35::1 (this system)
MLD version is 2
MLD Snooping
Multicast packets are addressed with multicast MAC addresses, which represent a group of devices, rather than one unique device.
Switches forward multicast frames out of all ports in a VLAN by default, even though there may be only some interested hosts, which is a
Multicast Listener Discovery Protocol
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